Metallic electrode.



13. WEINYTRAUB. METALLIC ELECTRODE. APPLICATION FILED Amm, 191.

l, 1 1 6,960. Patented Nov. 10, 1914.

WJTNEESES' v /NVENTUR 5%, EzE/:H/EL 4 DVE/NTRA /f/a@ @Y QM H/.S A TTUH NEY 'f TED s'rarns PATENT orrionf t EZEGHIEL WEIIN'ERUB, 0F LYNN', MASSACHUSETTS, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A COBPORAFION UF NEW YORK.

, not

METALLIC vELnonsens.

i Speeicatioii et', Letters Patent.

Patented Nov. 10, 1914.

To all whom it may concern.'

Be it known that I, Eznci-iinn l/VEINTRAUB, a, citizen of the United States, residing at Lynn, county of Essex, State of Massachu` setts, haveinvented certain new and useful Improvements in Metallic Electrodes, of which the following is a specification.

My present invention relates to electrodes for' use in vapor electric apparatus, particularly in mercury are recti-ers.

The invention has for its object to providean electrode which operates yas positive electrode or anode which shall be free from the tendency of becoming the seat of an arc when made negative in the presence of mercury in an exhausted space, and which shall ive rise to electrical disturbances such as fading?" .These objects are accomplished by'making the anodes of the appa-` ratus of metallic tungsten, preferably, drawn tungsten` I have discovered that it is incomparably `more difficult to establish a cathode spot of an arc in an exhausted space on the surface of tungsten than on the surface of any other material that I have tried. To illustrate this, let us suppose that a solid material such as carbon or iron, is brought in contact with mercury in an exhausted space, the solid material being connected tg the negative Side and the mercury to the positive side of a' source of current. Even at voltages as low as 100 volts and lower, 'a regular mercury arc isr formed with the cathode spot on the solid material. `With tungsten anodes it is impossible to get the cathode spot to form even with 500 volts and with very little resistance in series. With higher voltages the are will start with a cathode spot4 on the glass into which the leading-in wire is sealed rather than on the tungsten. This method of contact is the easiest way of producing a cathode spot on a solid metallic material. In the rectier the conditions are not so favorable to the formation of a cathode spot on the solid material and it ,takes 'a high voltage toproduce it, even in case of iron or graphite. The quantitative diiierence between the ease of formation of a cathode spot on iron, graphite, etc., as compared to tungsten, however, remains the same as that illustrated by the contact method.

The phenomenon of reverse arcing is very troublesome and limits the application of' the rectifier. with any given voltage to a certain maximum current, this current becomino' smaller as the voltage is increased; Any (I ple, the rectifier tube provided with aiiodesy of tungsten. The rectifier tube with container shown in the drawing is oa common form new well known in the art and requires no special description. The mercury cathode of the rectifier tube is at I and the starting electrodes at 2 and 3. The main anodes are arranged as usual in the upper ends oi'\y the outwardly and upwardly extending arms t 4 and 5. The anodes themselves as indicated by the numerals 6 and 7 and as has been mentioned, are made of metallic tungsten. The anodes are indicated as being hollow and as practically filling the upper part of the anode tubes in order to provide for more effective heat radiation.

As well understood by those skilled in the i art, the term fading is applied t0 a condition in a rectifier which causes the arc to start at a progressively higher voltage as it shifts from Vanode to anode. In other words, the tubes require a progressively higher voltage to operate, thus utilizing smaller and smaller proportion of the alter- I nating current. The tube finally goes out because the current utilized is not suiiicient to maintain the arc. I believe this diiiiculty with tungsten anodes of the usual size to be due to the fact that tungsten anodes oper-.

ate at a higher temperature than graphite anodes of the same size, possibly due to the fact that tungsten is a poorer radiator of heat energy than graphite and inost other materials. I, therefore, so proportion the extent of the anode surface with respect to the capacity or rating of the device thatthe anode will operate at a. temperature below cherrv red. As the anodes are not artificially cooled they necessarily are heated by the arc to a temperature above the mercury in a vacuum.

In mercury arc devicesprovided with anodes of tungsten a further` advantage is secured by the `fact that the Vacuum is not v affected by the giving oi of gases and, there fore, the tube 1s more readily exhausted as ing the binder by methods now Well understood in the art.

The appended claims are directed to the structural featuresfof the rectifier tube, but

claims on broader features of my invention such asthe rectifying system are not made, herein but are made in other applications and especiallyin application, Serial N o.

149,084, filed March 23, 1903.

- What I claim as new and desire to secure -by Letters Patent of the United States, is:-

`1. The combination of an evacuated con` tainer, a cathode of easily vaporizable mateboiling point O fv rial and a coperating anode consisting of tungsten and having a heat dissipating capacity proportioned with respect to the operating capacity of the device to enable sald anode tov operate below cherry red heat, but abovethe v boiling point of mercury 1n 'a VilCllllm. 'i' a 2. The combination of an evacuated container having a mercury cathode and elec# trodcs operating as anodes with respect to said cathode but subjected to differences of potential with respect to each other, said anodes consisting of tungsten and having a sufficient heat dissipating capacity to enable them to operate at a Ytemperature below cherry red heat, but above of mercury in a vacuum. 3. The method of preventing fading of a periodically shifting vapor electric arc'operated between a mercury cathode and cooperating tungsten anodes alternatin in potential which consists in dissipating' eat from said anodes at a rate proportioned to lmaintain said anodes at a temperature below cherry red. In witness whereof, I have hereuntg set my hand this third day of April, 1912. i

y EZECHIEL WEINTRAUB. Witnesses:

JOHN A. MoMANUs, Jr., ROBERT SHAND. 

